As it happens, I have a lot of opinions about both what good game design should look like and how projects like this should be developed. Here are ideas I consider core:

Game design principles

• Use what's proven. This is not a place for experimental mechanics.
• Don't try to create a life simulator. Think about interesting gameplay over realism.
• Treat this as an engine of experience. Maximize player emotions.
• Minimize obvious choices and pointless actions.
• Don't overload players. Offload as much work as possible to calculations.
• Make every character at least moderately useful in the vast majority of situations.
• Apply the same rules to every character in the world.

General principles

• Be a perfect place for escapism.
• Make game playable around a fire in a forest with no internet connection.
• Care about freedoms of users.
• Be as open as reasonable.
• Provide platform for others to create and share.

This is what I use when making decisions for the project. This is not set in stone. As development continues, I expect these to evolve as well.

I hope by following this I will make something enjoyable to use, that helps people connect and benefits all who enjoy this hobby.